1. Field of the Invention
The present invention relates to a joining structure for joining pipes in a treatment tool for use in an endoscope, for example, a joining method, and a method of manufacturing a resin member for the joining structure.
2. Description of the Related Art
In the field of medicine, endoscope systems have conventionally been used to observe organs in subjects such as patients. Some of such endoscope systems are known to include a flexible and elongated insertion portion that is to be inserted into the body cavity of the subject, an imaging element that is provided at the distal end of the insertion portion to capture an in-vivo image, and an external device that is connected to the insertion portion via a cable to perform image processing on the in-vivo image taken by the imaging element and displays the in-vivo image on a display unit or the like. Doctor or the like can insert a treatment tool into the insertion portion and operate the same while watching the in-vivo image captured by the imaging element, thereby to apply specified treatment to the inside of the subject's body.
Examples of the treatment tools for use in the endoscope system include a syringe. The syringe is formed by pressing a pipe to be inserted into the insertion portion, into the inside of a pipe grasped by a doctor or the like to join the pipes (for example, refer to Japanese Patent Application Laid-open No. 53-49884).
The syringe may also be made of resin and metal. To join such a resin and metal, there has been disclosed a technique for pressing a metal pipe into a hollow portion of a resin molded product in which the hollow portion is formed (for example, refer to Japanese Patent Application Laid-open No. 11-223163). However, the resin molded product has a problem that the diameter of the hollow portion are changed by sink marks (recessions on a thick surface) during the molding, which leads to reduction in airtightness between the pipes.
In this regard, to improve airtightness between the pipes, there has been disclosed a technique for reducing a resin molded product in thickness by forming a hollow space between its outer circumference and hollow portion, thereby to suppress occurrence of sink marks on the resin molded product during the molding (for example, refer to Japanese Patent Application Laid-open No. 59-84385).
There has also been disclosed a technique for suppressing warpage of a molded product by adjusting the cutting position of a gate as a resin inlet and the amount of a resin (for example, refer to Japanese Patent Application Laid-open No. 11-192711). According to the technique disclosed in Japanese Patent Application Laid-open No. 11-192711, a molding process is carried out such that a resin is poured via an opening extended along a longitudinal direction of the molded product, from a direction orthogonal to the longitudinal direction of the molded product.